This invention relates to an assembly of a safety rail for an access hatch and in particular, though not exclusively, for an access hatch for personnel whereby personnel may, for example, gain access to the roof of a building from within the building or vice versa. It relates also to a safety hatch assembly comprising a safety rail assembly and an access hatch.
For an installation comprising a hatch of a size intended for through movement of personnel, or a hatch through which personnel may inadvertently fall, for example a hatch opening in the top of a liquid storage tank, it is known to provide the hatch with a guard rail firmly bolted or otherwise rigidly secured to the roof surface or to the hatch frame.
Whilst it is thereby possible to provide an effective safety rail installation, a need for expenditure and care of installation arises due to the requirement either to bolt to an existing surface surrounding the hatch frame or to secure to the hatch frame. The need for expenditure and care is particularly apparent in the case of a retrofit requirement in which it is necessary to provide an existing access hatch with a surrounding safety rail installation
An object of the present invention is to provide a safety rail assembly for an access hatch, and a safety hatch assembly of a safety rail assembly and access hatch in which the safety rail assembly can be provided in a more cost effective and simpler manner than hitherto.
In accordance with one aspect of the present invention there is provided a safety rail assembly for an access hatch of a kind comprising a hatch frame which defines an opening, said safety rail assembly being adapted to extend around at least a part of a hatch frame thereby to safeguard personnel from inadvertent entry into the hatch opening from at least two mutually perpendicular directions, said safety rail assembly comprising guard members which in use extend at least in part substantially horizontally, and support members for supporting the guard members at a position elevated above the hatch frame, said support members each having associated therewith a foot portion for resting in a free-standing manner on a support surface surrounding the hatch frame, and said support members having a resistance to toppling in a direction towards or a direction away from the opening defined by the frame by at least one of:
structural connection to a part of the safety rail assembly at an opposite side of the frame.
co-operation of the safety rail assembly with an abutment surface defined by the hatch frame.
The access hatch may comprise a closure member selectively moveable to open or close an opening defined by said frame
The guard members may be of a rigid type and may be rigidly interconnected to one another and to support members whereby the safety rail assembly is a substantially rigid assembly in which the safety rail members at one side of an access hatch frame act as a counter balance or stabiliser to inhibit toppling movement of the safety rail members of an adjacent or opposite side of the safety rail assembly in a direction towards or away from an opening defined by the hatch frame.
Examples of rigid type guard members are metal bars or tubes and also panels of substantially rigid material such as metal plates or grids. A guard member in the form of a panel may be secured to a support member at two or more positions spaced along the length of the support member.
The safety rail members of an adjacent or opposite side may provide said resistance to toppling and said stabilisation either by virtue of their weight and spacing from the stabilised side, or, for example, by engagement with an abutment surface defined by the hatch frame.
It is not, however, essential that the safety rail assembly comprises said rigid assembly of members. A support member may be provided with a foot portion which, relative to the vertical position of an upwardly extending portion of the support member, extends outwards, away from the hatch frame. Thus the foot portion may comprise a flat metal plate which is permanently secured, e.g. welded, to an end of a metal tube or rod that extends vertically upwards to support a guard member, or the foot portion may, for example, be a plate which has secured thereto or formed integrally therewith a stub post or socket to which the lower end of a tube or rod may be secured in a manner known per se. Resistance to toppling in an direction towards the hatch opening is thereby achieved in consequence of the counter-balance might effect of the foot portion.
The support member may comprise a foot portion which is adapted to contact an abutment surface of a hatch access frame in a manner that resists toppling of the support member away from the opening. The access frame may comprise a rim section which outwardly overhangs from a core section of the frame extending upwards from the roof surface there by to define an overhang the underneath surface of which may act as an abutment for engagement by a confronting, e.g. a n upper, surface of an interlock member such as may be comprised by a support member foot portion. The access hatch frame preferably provides said overhangs and abutment surfaces at least at two opposite sides of the frame.
Thus, in accordance with a further aspect of the invention there is provided a safety rail assembly for an access hatch of a kind comprising a hatch frame which defines an opening, said safety rail assembly being adapted to extend around at least a part of a hatch frame thereby to safeguard personnel from inadvertent entry into the hatch opening from at least two mutually perpendicular directions, said safety rail assembly comprising guard members which in use extend at least in part substantially horizontally, and support members for supporting the guard members at a position elevated above the hatch frame, said hatch frame being provided at at least two opposite sides thereof with abutment surfaces which in use face substantially downwards towards but are spaced from a support surface surrounding the hatch frame, and said safety rail assembly having associated therewith interlock members arranged in use to lie between said abutment surfaces and the support surface surrounding the hatch frame whereby said interlock members and abutment surfaces are interengageable to resist upwards movement of the safety rail assembly in a direction away from the support surface.
An interlock member may be comprised by the aforedescribed foot member(s) provided at the lower end of a support member to rest on the support surfaces surrounding the hatch frame. Alternatively it may be comprised by an auxiliary member secured to or forming part of a lower end region, e.g. foot position, of a support member. The auxiliary member may be a connection member which extends between and which may rigidly interconnect two of the support members.
Particularly, but not necessarily only, if a free-standing support member is provided with stability and resistance to toppling by means of a foot portion thereof, it is not essential that the guard members are rigid. Thus one or more guard members at respective sides of the safety rail assembly may be comprised by a flexible member such as a metal chain or cable.
The guard members may extend between support members at only some of the sides of the frame, e.g. to inhibit inadvertent entry to a hatch opening from two or three directions. Alternatively guard members may be provided to form a safety barrier which inhibits entry from anyone of four mutually perpendicular directions.
For an access hatch which is a personnel access it is envisaged that typically one side of the frame will be devoid of a guard member. The present invention teaches, however, that even if one side of an access hatch frame is devoid of a guard member, that side may be provided with a connection member arranged to extend between and inhibit separation of the respective ends of two sides of the safety rail assembly. Thus if the support members are of a kind having foot portions engageable with an abutment surface of the access hatch framer the connection member may serve to ensure that said foot portions remain in a position in which they are in engagement or engageable with an abutment surface of the frame and cannot readily be displaced outwards, away from the frame to a position at which they cease to be engageable with the frame. Said connection member may serve also to rigidly interconnect two support members such that one support member acts at least in part as a counter balance to assist in resisting toppling movement of the other of the two support members.
Said connection member preferably is provided close to the surface on which the free-standing support members rest. More particularly it is preferred that the connection member does not extend above said surface to a height greater than the height to which the access hatch frame extends above said surface. In the case of an access frame having an overhanging rim portion, said connection member may be positioned to lie in a recess defined by the side of the access frame underneath said overhang. Overhangs may be provided around sides of the frame at different spacings from the support surface whereby one or more overhangs allows a connection member readily to be accommodated in an interlock type position whilst one or more other overhangs closely overlie for example a support member foot plate.
Typically the access hatch frame will be of a rectangular, eg. square or oblong, shape. However it is to be understood that the teaching of the subject invention may be applied also to an access hatch frame of another shape, such as a circular, oval or hexagonal shape, in which case the references herein to sides of the access hatch frame are to be interpreted as sides perpendicular to each of four mutually perpendicular directions from which personnel might inadvertently approach the access hatch.
Preferably the support members are positioned such that even when subjected to forces causing them to tend to slide over the support surface surrounding the access hatch frame, they are at or move to a position in contact with the access hatch frame thereby to inhibit said sliding movement in at least three, and preferably four mutually perpendicular directions. Thus, without the need permanently to secure the support members either to the access hatch frame or the surrounding support surface, it is ensured that the safety rail assembly remains correctly positioned relative to the access hatch frame.
In addition to a safety rail assembly for an access hatch as herein defined the present invention provides also a safety hatch assembly and components therefor comprising a safety rail assembly and an access hatch wherein the safety rail and access hatch assemblies are inter-engageable thereby to enhance the stability of the safety rail.